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111.
Lee SW Lee K Seomoon D Kim S Kim H Kim H Shim E Lee M Lee S Kim M Lee PH 《The Journal of organic chemistry》2004,69(14):4852-4855
Tetraorganoindates, which were prepared easily from the reaction of 1 equiv of InCl(3) with 4 equiv of organometallics, could be employed as effective nucleophilic cross-coupling partners in Pd-catalyzed carbonylative cross-coupling reactions with a variety of organic electrophiles. The present method gave unsymmetrical ketones and 1,4-diacylbenzenes in good yields with highly efficient transfer of almost all the organic groups attached to the indium under a carbon monoxide atmosphere in THF at 60 degrees C. 相似文献
112.
113.
Two ligand exchange chiral stationary phases (CSPs) based on (S)-leucinol derivative, sodium N-((S)-1-hydroxymethyl-3-methylbutyl)-N-undecylaminoacetate, and (R)-phenylglycinol derivative, sodium N-((R)-2-hydroxy-1-phenylethyl)-N-undecylaminoacetate, covalently bonded to silica gel have been successfully applied in the resolution of nine -hydroxycarboxylic acids. The latter was more effective than the former, the separation factors () being 1.05 to 2.12 while the resolution factors (RS) varying from 0.18 to 5.29 on the latter. The chromatographic resolution behaviors were dependent on the type and the content of organic modifier and the content of CuSO4 in aqueous mobile phase and the column temperature. A possible chiral recognition mechanism was also proposed based on the chromatographic resolution behaviors. 相似文献
114.
Drop retraction methods are popular means of measuring the interfacial tension between immiscible polymers. Experiments show that two different drop retraction methods, imbedded fiber retraction (IFR) and deformed drop retraction (DDR), give inconsistent results when a surfactant is present on the surface of the drop. These inconsistencies are deemed to be due to dilution of the surfactant and due to gradients in interfacial concentration of surfactant along the drop surface. This physical picture is quantified for the simple case of a Newtonian drop in a Newtonian matrix, with an insoluble, nondiffusive surfactant at the interface. The drop is deformed in computational fluid dynamics simulations by shearing the matrix, and then allowed to retract. Dilution and interfacial tension gradients effects are found to be especially large at the early stages of retraction, making IFR unsuitable for measuring the interfacial tension of surfactant-laden interfaces. The effects of surfactant dilution and gradients are found to persist even at late stages of retraction, causing the DDR method to underestimate the equilibrium interfacial tension significantly. The largest underestimates occur when the drop viscosity is lower than the matrix viscosity. 相似文献
115.
Eupatilin (5,7-dihydroxy-3',4',6-trimethoxy flavone) is an active ingredient of an ethanol extract of Artemisia asiatica (DA-9601) that is used in the treatment of gastritis. In vitro and in vivo metabolism of eupatilin in the rats has been studied by LC-electrospray mass spectrometry. Rat liver microsomal incubation of eupatilin in the presence of NADPH and UDPGA resulted in the formation of four metabolites (M1-M4). M1, M2, M3 and M4 were tentatively identified as 3'- or 4'-O-demethyl-eupatilin glucuronide, eupatilin glucuronide, 6-O-demethyleupatilin and 3'- or 4'-O-demethyl-eupatilin, respectively. Those metabolites from in vitro study were also characterized in bile, plasma or urine samples after an intravenous administration of eupatilin to rats. In rat bile, plasma and urine samples, eupatilin glucuronide (M2) was a major metabolite, whereas M3, M4 and M4 glucuronide (M1) were the minor metabolites. 相似文献
116.
Jaechang Lim Sang-Yeon Hwang Seokhyun Moon Seungsu Kim Woo Youn Kim 《Chemical science》2020,11(4):1153
Searching for new molecules in areas like drug discovery often starts from the core structures of known molecules. Such a method has called for a strategy of designing derivative compounds retaining a particular scaffold as a substructure. On this account, our present work proposes a graph generative model that targets its use in scaffold-based molecular design. Our model accepts a molecular scaffold as input and extends it by sequentially adding atoms and bonds. The generated molecules are then guaranteed to contain the scaffold with certainty, and their properties can be controlled by conditioning the generation process on desired properties. The learned rule of extending molecules can well generalize to arbitrary kinds of scaffolds, including those unseen during learning. In the conditional generation of molecules, our model can simultaneously control multiple chemical properties despite the search space constrained by fixing the substructure. As a demonstration, we applied our model to designing inhibitors of the epidermal growth factor receptor and show that our model can employ a simple semi-supervised extension to broaden its applicability to situations where only a small amount of data is available.We propose a scaffold-based graph generative model for designing novel drug candidates that include the desired scaffold as a substructure. 相似文献
117.
Jin Y Yoon I Seo J Lee JE Moon ST Kim J Han SW Park KM Lindoy LF Lee SS 《Dalton transactions (Cambridge, England : 2003)》2005,(4):788-796
The NO2S2-donor macrocycle (L1) was synthesised from the ring closure reaction between Boc-N-protected 2,2'-iminobis(ethanethiol) (3) and 2,2'-(ethylenedioxy)bis(benzyl chloride) (4) followed by deprotection of the Boc-group. alpha,alpha'-Dibromo-p-xylene was employed as a dialkylating agent to bridge two L1 to yield the corresponding N-linked product (L2). The X-ray structure of L2 (as its HBr salt) is described. A range of Cd(II) and Hg(II) complexes of L1 (6-9) and L2 (10-12) were prepared and characterised. Reaction of HgX2 (X = Br or I) with L1 afforded [Hg(L1)Br]2[Hg2Br6].2CH2Cl2 6 and [Hg(L1)I(2)] 7, respectively. For 6, the Hg(II) ion in the complex cation has a distorted tetrahedral coordination environment composed of S2N donor atoms from L1 and a bromo ligand. In 7 the coordination geometry is highly distorted tetrahedral, with the macrocycle coordinating in an exodentate manner via one S and one N atom. The remaining two coordination sites are occupied by iodide ions. [Hg(L1)(ClO4)]ClO4 8 was isolated from the reaction of Hg(ClO4)2 and L1. The X-ray structure reveals that all macrocyclic ring donors bind to the central mercury ion in this case, with the latter exhibiting a highly distorted octahedral coordination geometry. The O2S2-donors from the macrocyclic ring define the equatorial plane while the axial positions are occupied by the ring nitrogen as well as by an oxygen from a monodentate perchlorato ion. Reaction of Cd(NO3)(2).4H2O with L1 afforded [Cd(L1)(NO3)2](.)0.5CH2Cl2 9 in which L1 acts as a tridentate ligand, binding exo-fashion via its S2N donors. The remaining coordination positions are filled by two bidentate nitrate ions such that, overall, the cadmium is seven-coordinate. Reactions of HgX2(X = Br or I) with L2 yielded the isostructural 2 : 1 (metal : ligand) complexes, [Hg2(L2)Br4] 10 and [Hg2(L2)I(4)] 11. Each mercury ion has a distorted tetrahedral environment made up of S and N donors from an exodentate L2 and two coordinated halides. Contrasting with this, the reaction of L2 with Cd(NO3)(2).4H2O yielded a 1-D coordination network, {[Cd2(L2)(NO3)4].2CH2Cl2}n 12 in which each ring of L2 is exo-coordinated via two S atoms and one N atom to a cadmium ion which is also bound to one monodentate and one bidentate nitrate anion. The latter also has one of its oxygen atom attached to a neighboring cadmium via a nitroso (mu2-O) bridge such that the overall coordination geometry about each cadmium is seven-coordinate. The [Cd(L2)0.5(NO3)2] units are linked by an inversion to yield the polymeric arrangement. 相似文献
118.
S. S. Yun H. B. Yang J. H. Yoo H. Moon 《Journal of Radioanalytical and Nuclear Chemistry》1997,218(2):177-181
The complexation of Eu3+ and Am3+ ions with the humic acids has been investigated at various pH (4.0, 4.5, 5.0, 5.4) in 0.1M NaClO4 solution using solvent extraction technique. Two humic acids are used in this study: humic acid extracted from the soil of Taejon on the Okchon Basin of Korea (TJHA) and commercially available one from Aldrich Chemical Co. (AHA). The total carboxylate group concentrations were determined to be 3.58 meq/g and 4.59 meq/g for Taejon and Aldrich humic acids, respectively. The conditional stability constants (log 1 and log 2), dependent on the pH of the solution, of the complexes of Eu3+ and Am3+ ions with the humic acids have been determined at the ionic medium of 0.1M NaClO4. The values of stability constants with the degree of ionization of TJHA for Eu and Am complexes are quite well agreed with those of Lake Bradford humic acid (LBHA), indicating that structural characteristics of TJHA and LBHA may be quite similar to one another. 相似文献
119.
Three new pregnane glycosides, cynatroside A ( 1 ), cynatroside B ( 2 ), and cynatroside C ( 3 ), isolated from the roots of Cynanchum atratum (Asclepiadaceae), were characterized as 7β‐{[O‐α‐L ‐cymaropyranosyl‐(1→4)‐O‐β‐D ‐digitoxopyranosyl‐(1→4)‐β‐D ‐oleandropyranosyl]oxy}‐3,4,4a,4b,5,6,7,8,10,10a‐decahydro‐6α‐hydroxy‐4b‐ methyl‐2‐(2‐methyl‐3‐furyl)phenanthren‐1(2H)‐one ( 1 ), 7β‐{[O‐β‐D ‐cymaropyranosyl‐(1→4)‐O‐α‐L ‐diginopyranosyl‐(1→4)‐β‐D ‐cymaropyranosyl]oxy}‐3,4,4a,4b,5,6,7,8,10,10a‐decahydro‐2,6α‐dihydroxy‐4b‐methyl‐2‐(2‐methyl‐3‐furyl)phenanthren‐1(2H)‐one ( 2 ), and 7β‐{[O‐α‐L ‐cymaropyranosyl‐(1→4)‐O‐β‐D ‐digitoxopyranosyl‐(1→4)‐β‐L ‐cymaropyranosyl]oxy}‐3,4,4a,4b,5,6,7,8,10,10a‐decahydro‐2,6α‐dihydroxy‐4b‐methyl‐2‐(2‐methyl‐3‐furyl)phenanthren‐1(2H)‐one ( 3 ), respectively. In addition, ten known constituents were identified, i.e., cynascyroside D ( 4 ), glaucoside C ( 5 ), glaucoside D ( 6 ), atratoside A ( 7 ), 2,4‐dihydroxyacetophenone ( 8 ), 4‐hydroxyacetophenone ( 9 ), syringic acid ( 10 ), azelaic acid ( 11 ), suberic acid ( 12 ), and succinic acid ( 13 ). Among these compounds, 1 – 4 significantly inhibit acetylcholinesterase activity. 相似文献
120.
Spatially complex, temporally chaotic dynamics of N-coupled impact oscillators connected by a string are studied experimentally using a discrete measure of the motion for each of the masses. For N=8, a binary assignment of symbols, corresponding to whether or not the masses impact an amplitude constraint, is used to code the spatial pattern as a binary number and to store its change in time in a computer. A spatial pattern return map is then used to observe the change in spatial patterns with time. Bifurcations in spatial impact patterns are observed in this experiment. An entropy measure is also used to characterize the dynamics. Numerical simulation shows behavior similar to the experimental system. 相似文献